The present invention relates to a process for the production of alcoholic beverages, especially beer and whiskey.
Alcoholic beverages such as beer can be manufactured from malted and/or unmalted barley grains. Malt, in addition to yeast, contributes to flavour and colour of the beer. Furthermore, malt functions as a source of fermentable sugar and enzymes. Whether malt is used in the brewing process depends on the type of beer and on the country where the beer is produced. In African countries, for example, there is no tradition of using malt.
The general process of malting and brewing is recently described by R. C. Hoseney (Cereal Foods World, 39(9), 675-679, 1994). Malting is the process of controlled germination followed by controlled drying of the barley grain. Grain is converted into malt by successive steps of steeping, germination, growth and drying (kilning). In this respect, the germination step is important to obtain expression of a series of enzymes which enables modification of the endosperm. This modification produces fermentable carbohydrates.
The subsequent drying/heating step of the malting process produces flavour and colour due to non-enzymatic browning (Maillard) reactions.
The process of malting is a very complicated and costly part of the beer production process. Several disadvantages of the malting process can be mentioned:
the enzyme level of malt is variable which leads to unpredictable results,
not every enzyme activity which is desirable is formed or is formed in sufficient amounts during germination, which makes enzyme supplementation necessary,
conditions which favour high flavour and colour may be deleterious for enzyme activity of the malt,
the process is expensive,
10-20% loss in weight occurs during germination, due to respiration and growth of rootlets (which are removed during cleaning of the malt),
it is not possible to produce malt at any place which is desirable, because of unfavourable climate conditions,
the use of malt can lead to colloidal instability because of solubilization of protein by protease present in the malt,
formation of biogenic amines can occur (J. Food Science 59(5), 1104-1107, 1994), which may lead to e.g. histaminic intoxication.
Traditionally, malt was the only source of fermentable carbohydrates and enzymes, and in many countries it still is. However, to date more and more beers are produced using other sources of carbohydrates than malt and/or barley, i.e. virtually any starch source or liquefied/degraded starch, the so-called adjuncts. Since malt not only functions as a source of fermentable carbohydrate, but also as a source of enzymes, alternative enzyme sources have to be provided upon substitution of more than approximately 50% malt with unmalted barley and/or with adjuncts. Moreover, malt gives the beer flavour and colour.
In the production of malt there is a trade-off between flavour and colour and enzyme activity. A malt providing high flavour and dark colour can only be produced after more extensive drying at relatively high temperatures. These are conditions which are deleterious for the activity of an enzyme. Thus the supplementation of enzymes from an exogenous source is necessary from several points of view. In that respect, the use of microbial enzymes has been common practice for some time. For example, for brewing beer grains and/or malted grains are liquefied and saccharified in order to yield fermentable sugars. Liquefaction steps may be improved by the use of thermostable alpha-amylases as described in for instance U.S. Pat. Nos. 4,285,975 or 5,180,669. Also proteases are used to increase the amount of freely available nitrogen in the wort to improve fermentation.
Apart from starch other polysaccharides are present in cereal grains as for example xcex2-glucans (Henry, R. J. et al. J. Sci. Food Agric. 36, 1243-1253, 1985). The xcex2-glucanases present in malt are not sufficiently thermostable to be active during the brewing process. These xcex2-glucans are highly viscous and give wort and beer filtration problems. This is the reason why microbial xcex2-glucanases are widely used in the brewing process.
Non-starch polysaccharides also include pentosans, the structure of which has been widely studied recently (Gruppen, H. et al. Carbohydr. Res. 233, 45-64, 1992), in particular those of barley and malt (Vietor, R. J. et al. Carbohydr. Res. 254, 245-255, 1994). A pentosanase from Penicillium emersonii has been said to improve the production and extraction of fermentable sugars in brewing (GB 2,150,933).
The use of xylanase B to improve wort quality has also been mentioned in WO94/14965.
Despite the advance which has been made in this area, there is still a need for methods of beer brewing with enzyme preparations for use therein.
The present invention discloses a process for the production of alcoholic beverages, such as beer, to which a mixture of enzymes is added, which mixture comprises at least an endo-xcex2(1,4)-xylanase, an arabinofuranosidase, an alpha-amylase, an endo-protease and a xcex2-(1,3;1,4)-glucanase, optionally also containing a saccharifying amylase and/or an exo-peptidase. Preferably the enzymes that are necessary for the beer production process are provided by transgenic seeds.
The present invention further discloses transgenic seeds expressing the enzymes necessary in the beer production process.